Test HY: Generator/Regulator System: Testing

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

1) KOER & Continuous Memory DTC P1246: Verify Generator Drive Function
Check generator drive belt condition and tension. Start engine and verify generator is turning. Repair as necessary. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If no faults are found, go to next step.

2) Verify Charging System Is EEC Controlled

Turn ignition switch to OFF position. Disconnect negative, then positive battery cable. Disconnect generator connector. Using a DVOM, measure resistance between BATT-SENSE and GEN-COM circuits at generator connector. See Figure-Figure . If resistance is 950-1050 ohms, go to next step. If resistance is not 950-1050 ohms, replace generator/regulator assembly.

3) Check Battery Sense Voltage At Battery

Reconnect generator connector. Reconnect battery cables to battery. Using a DVOM, measure voltage between battery terminals. Note voltage measurement. Using a DVOM, measure voltage between negative battery terminal and BATT-SENSE circuit at generator harness connector. If voltage is within .5 volt (plus or minus) of battery voltage measurement, go to next step. If voltage is not within .5 volt of battery voltage measurement, repair BATT-SENSE circuit as necessary.

4) Check Generator Failure Mode

Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Ensure all accessories (electrical loads) are off. Using scan tool, access GFSF PID from PID/DATA MONITOR & RECORD menu. Start engine and raise engine speed to 2000 RPM. Note GFSF PID value. Wiggle and bend wiring harness between generator and PCM. Fault is indicated by a change in GFSF PID value. If a fault is indicated, go to next step. If no fault is indicated, check charging system and repair as necessary. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.

5) Check GEN-MON & GEN-COM Circuits For Short To PWR

Turn ignition switch to OFF position. Disconnect PCM connector(s). Disconnect generator connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and GEN-COM and GEN-MON circuits at PCM harness connector. See Figure-Figure . If both voltage measurements are .5 volt or less, go to next step. If either voltage measurement is more than .5 volt, repair short to PWR in affected circuit.

6) Check GEN-COM & GEN-MON Circuits For Short To GND

Turn ignition switch to OFF position. Using a DVOM, measure resistance between negative battery terminal and GEN-COM and GEN-MON circuits at PCM harness connector. If both resistance measurements are more than 10 k/ohms, go to next step. If either resistance measurement is 10 k/ohms or less, repair short to GND in affected circuit.

7) Check GEN-COM & GEN-MON Circuits For Open

Using a DVOM, measure resistance of GEN-COM and GEN-MON circuits between PCM harness connector and generator harness connector. If both resistance measurements are less than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open in affected circuit.

8) Check GEN-MON Signal

Reconnect all connectors. Start engine and allow to idle. Using scan tool, access GFS PID from PID/DATA MONITOR & RECORD menu. If GFS PID (duty cycle) is 6-98 percent, go to next step. If GFS PID (duty cycle) is not 6-98 percent, replace generator/regulator assembly.

9) Check GEN-COM Signal

With engine idling, access ILC (Explorer & Mountaineer) or GENFDC (all others) PID from PID/DATA MONITOR & RECORD menu. Observe ILC or GENFDC PID value, while cycling headlights on and off. If ILC or GENFDC PID duty cycle reading switched from zero to 99 percent, fault is unable to be duplicated at this time. Go to TEST Z, step 1) . If ILC or GENFDC PID duty cycle reading did not switch from zero to 99 percent, replace PCM.